Sheet for Decoration Simultaneous with Injection Molding and Decorated Resin Molding

ABSTRACT

The present invention provides a laminate-type decorative sheet for use in simultaneous decoration and injection molding, including a base film and at least a decorative layer provided on the base film, the decorative sheet having an elongation at break as measured at 25° C. of 3 to 10%, and an elongation at break as measured at 120° C. of 200% or more. 
     The laminate-type decorative sheet exhibits good conformability to the molding surface of a mold during the course of preforming, and is less likely to produce wrinkling, blistering, breakage, etc. when laminated on and united with a resin molding through injection molding. In addition, the decorative sheet enables easy trimming.

FIELD OF THE INVENTION

The present invention relates to a sheet which is employed forsimultaneous decoration of a molded article during the injection moldingprocess (hereinafter the sheet may be referred to as a “decorative sheetfor simultaneous decoration and injection molding”), and to a decoratedresin molded product. More particularly, the present invention relatesto a laminate-type decorative sheet suitable for forming a decoratedresin molded product through simultaneous decoration and injectionmolding, and to a decorated resin molded product formed by use of thedecorative sheet.

BACKGROUND ART

Conventionally, simultaneous decoration and injection molding has oftenbeen employed for decoration of a resin molding having a surface ofcomplicated shape (e.g., a three-dimensional curved surface) (see, forexample, Patent Documents 1 and 2). Simultaneous decoration andinjection molding is a method in which, during the course of injectionmolding, a decorative sheet placed in a mold is united with a moltenresin injected into the cavity of the mold, whereby the surface of aresin molding is decorated. In general, the simultaneous decoration andinjection molding method is roughly classified into a laminatedecoration method and a transfer decoration method, according to thestructure of a decorative sheet to be united with a resin molding.

In the laminate decoration method, the whole decorative sheet includinga base film and a decorative layer provided thereon is laminated on thesurface of a resin molding so that the decorative sheet is united withthe molding. The decorative sheet to be employed is a decorativelaminate sheet.

An example laminate-type simultaneous decoration and injection moldingmethod will now be described with reference to FIGS. 2 and 3. FIGS. 2and 3 are explanatory views showing an example of the molding step ofthe simultaneous decoration and injection molding method. A simultaneousdecoration and injection molding apparatus 60 includes a female mold 70,and a male mold 80 which is disposed laterally to the mold 70 so as toface the mold 70. The female mold 70 has a cavity 72 having a shapecorresponding to the contour of a molding to be formed, and includessuction holes 74 which extend throughout the mold 70 and are open to thecavity 72. The female mold 70 is adapted to be reciprocally moved bymeans of a reciprocating apparatus 75 formed of, for example, afluid-pressure cylinder in directions toward and away from the male mold80. The male mold 80 has a core section 82 which is inserted into thecavity 72, the core section 82 including a gate 84 therein for injectinga molten resin in the cavity. If necessary, a reciprocally movableheating plate 90 is provided between the female mold 70 and the malemold 80.

In order to perform decoration simultaneously with injection molding bymeans of the apparatus 60, firstly, a decorative sheet 100 is providedon the female mold 70 so as to face the male mold, and, if necessary,the decorative sheet 100 is heated and softened at an appropriatetemperature by means of the heating plate 90. Subsequently, thedecorative sheet 100 is sandwiched by the female mold 70 and the heatingplate 90, to thereby close the opening of the cavity 72. The thus-closedcavity is evacuated through the suction holes 74 provided in the femalemold 70, and, if desired, pressurized air is supplied to the sheetthrough a vent provided in the heating plate 90. Both molds aregenerally heated to about 30 to about 50° C.

Through this procedure, as shown in FIG. 3, the decorative sheet 100 isstretched along the inner wall of the cavity 72 so as to come into closecontact therewith. This procedure is generally called “preforming,” inwhich a softened sheet is generally stretched up to about 200%.Subsequently, the heating plate 90 is withdrawn, and, as shown in FIG.3, the female mold 70 is moved toward the male mold 80 so that the moldsare united together, followed by mold clamping. Thereafter, a fluidizedresin molding material P is injected, through the gate 84 provided inthe male mold 80, into a cavity formed between the female mold 70 andthe male mold 80 until the cavity is filled with the material, and thusinjection molding is performed.

Through this procedure, the decorative sheet 100 placed in the femalemold 70 is attached to and united with the thus-injected resin. Aftercompletion of injection molding, the molds are separated from eachother, to thereby remove, from the molds, a molding whose outer surfaceis coated with the decorative sheet 100. Thus, laminate-type decorationis completed.

In the aforementioned simultaneous decoration and injection moldingmethod, important requirements for formation of a good molded productare that the decorative sheet 100 can be stretched along the inner wallof the cavity 72 so as to come into close contact therewith during thecourse of preforming or molten resin injection (i.e., moldability of thesheet), and that the decorative sheet is not deformed through stretchingto an extent exceeding that necessary for fitting the sheet to the shapeof the mold, which deformation may be caused by, for example,vacuum/pressure effect, or tension due to the pressure or shear stressof the molten resin. These requirements are particularly important inthe case of molding by means of a mold having a large depth, since thedecorative sheet is subjected to deep drawing.

In the case of deep-draw molding. (i.e., in the case where the percentstretching of a decorative sheet is high), generally, such aresin-injection-molded product is required to be decorated so as toattain a drawn shape corresponding to a percent stretching of about 200to about 400% of the decorative sheet. In order to satisfy such arequirement, there have been proposed, for example, a decorative sheetformed of a material which has a yield point and which receives stressof a certain level or more after the yield point (see claims of PatentDocument 3), and as well a decorative sheet for molding formed of two ormore laminated films, the sheet exhibiting a peeling strength of acertain level or more at the interface between the sheet and a resin tobe molded, wherein a transparent acrylic film is provided on the filmwhich is bonded to the resin, and a pattern is formed between theacrylic film and the film which is bonded to the resin (see claims ofPatent Document 4). In order to sufficiently conform to the irregularsurface shape of the molded product, the aforementioned decorative sheetfor molding exhibits an elongation at break (percent stretching) ofabout 150 to 200% or more, or about 400% as maximum in the temperaturerange of 100 to 120° C., to which the decorative sheet is heated duringthe preforming or injection molding.

In general, a laminate-type decorative sheet having an area exceedingthe surface area of a molded product is bonded to the molded product.Therefore, the decorative sheet must be subjected to a step called“trimming” for cutting or removing an excess portion provided along theperiphery of the molded product. Such trimming is performed at about 0to about 40° C. (generally at room temperature (about 25° C.)). Theaforementioned decorative sheet disclosed in Patent Document 3 or 4,which exhibits an elongation at break (percent stretching) of about 150to about 200% or more as measured at 100 to 120° C., generally exhibitsan elongation at break (percent stretching) as high as 20% or more asmeasured at room temperature. When such a decorative sheet exhibiting anelongation at break (percent stretching) as high as 20% or more asmeasured at room temperature is employed, the decorative sheet poses aproblem in that an excess decorative sheet portion provided along theperiphery of a molded product fails be cut successfully during thecourse of trimming, and thus the excess decorative sheet portion remainson the molded product, or the decorative sheet is exfoliated at an endportion of the molded product.

Meanwhile, when a decorative sheet exhibiting low elongation at break asmeasured at 100 to 120° C. is employed, trimming of the sheet can bereadily performed, since the sheet generally exhibits low elongation atbreak as measured at room temperature. However, when such a decorativesheet is employed for deep-draw molding, the sheet fails to sufficientlyconform to surface irregularities of a molded product, and in somecases, the sheet is broken during the course of printing.

Patent Document 1: Japanese Patent Publication (kokoku) No. S50-19132

Patent Document 2: Japanese Patent Publication (kokoku) No. S61-17255

Patent Document 3: Japanese Patent No. 2690258

Patent Document 4: Japanese Patent No. 2965973

DISCLOSURE OF THE INVENTION

In view of the foregoing, an object of the present invention is toprovide a laminate-type decorative sheet which is suitable for forming adecorated resin molded product through simultaneous decoration andinjection molding; i.e., a decorative sheet which exhibits goodconformability to the molding surface of a mold during the course ofpreforming, which is less likely to produce wrinkling, blistering,breakage, etc. when laminated on and united with a resin molding throughinjection molding, and which enables easy trimming. Another object ofthe present invention is to provide a decorated resin molded productformed by use of the decorative sheet.

In order to achieve the aforementioned objects, the present inventorshave conducted extensive studies, and as a result have found that theabove-described problems are solved by a decorative sheet forsimultaneous decoration and injection molding, the sheet having anelongation at break as measured at 25° C. falling within a certainrange, and an elongation at break as measured at 120° C. of a certainlevel or more. The present invention has been accomplished on the basisof this finding.

Accordingly, the present invention provides:

-   (1) a laminate-type decorative sheet for use in simultaneous    decoration and injection molding, comprising a base film and at    least a decorative layer provided on the base film, the decorative    sheet having an elongation at break as measured at 25° C. of 3 to    10%, and an elongation at break as measured at 120° C. of 200% or    more;-   (2) a decorative sheet for simultaneous decoration and injection    molding as described in (1) above, which has an elongation at break    as measured at 25° C. of 3 to 7%;-   (3) a decorative sheet for simultaneous decoration and injection    molding as described in (1) or (2) above, which has an elongation at    break as measured at 120° C. of 200 to 400%;-   (4) a decorative sheet for simultaneous decoration and injection    molding as described in any of (1) to (3) above, wherein the base    film is formed of an acrylic resin composition;-   (5) a decorative sheet for simultaneous decoration and injection    molding as described in (4) above, wherein the acrylic resin    composition is a resin composition containing, as a primary    component, a polyacrylate and/or a polymethacrylate; and-   (6) a decorated resin molded product comprising a resin molding, and    a decorative sheet as described in any of (1) to (5) above, the    sheet being bonded onto the molding, wherein the decorative layer of    the decorative sheet is bonded to the molding.

According to the present invention, there can be provided a decorativesheet for simultaneous decoration and injection molding, which issuitable for forming a decorated resin molded product throughsimultaneous decoration and injection molding; i.e., a decorative sheetwhich exhibits good conformability to the molding surface of a moldduring the course of preforming, which is less likely to producewrinkling, blistering, breakage, etc. when laminated on and united witha resin molding through injection molding, which does not break duringprinting, and which enables easy trimming after molding. No excessportions of the decorative sheet remain on the molded product aftertrimming, and no exfoliation of the decorative sheet occurs at an edgeportion of the molded product.

A laminate-type decorated resin molded product of good quality can beprovided through simultaneous decoration and injection molding by use ofthe decorative sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an example of the structure ofthe decorative sheet of the present invention.

FIG. 2 is an explanatory view partially showing an example of themolding step of the simultaneous decoration and injection moldingmethod.

FIG. 3 is an explanatory view partially showing an example of themolding step of the simultaneous decoration and injection moldingmethod.

DESCRIPTION OF REFERENCE NUMERALS

1. Base film

2. Decorative layer

3. Adhesive layer

100. Decorative sheet

60. Simultaneous decoration and injection molding apparatus

70. Female mold

72. Cavity

74. Suction hole

75. Reciprocating apparatus

80. Male mold

82. Core section

84. Gate

90. Heating plate

P. Resin molding material

BEST MODE FOR CARRYING OUT THE INVENTION

The decorative sheet for simultaneous decoration and injection moldingof the present invention includes a base film and at least a decorativelayer provided thereon, and, if necessary, further includes an adhesivelayer. The decorative sheet has, for example, a cross-sectionalstructure shown in FIG. 1.

A characteristic feature of the decorative sheet for simultaneousdecoration and injection molding of the present invention resides inthat the sheet has an elongation at break as measured at 25° C. of 3 to10%. When the elongation at break as measured at 25° C. is less than 3%,the sheet enables easy trimming, but exhibits low strength. Therefore,in some cases, the sheet would be broken due to tensile force applied tothe base film when the decorative layer is formed on the base filmthrough printing, or the sheet would be broken when the sheet is fed toan apparatus for preforming or simultaneous decoration and injectionmolding. In some cases, breakage tends to occur during production of thebase film, and difficulty is encountered in winding up the sheet.

Meanwhile, when the elongation at break as measured at 25° C. exceeds10% (particularly 20% or more), trimming is difficult to perform; i.e.,the sheet fails to be cut along the periphery of a molded product duringthe course of trimming, and thus a portion of the sheet could remain onthe molded product, or the sheet could be exfoliated at an end portionof the molded product. When the elongation at break as measured at 25°C. is more than about 10% to about 20%, generally, trimming isrelatively easily performed. However, depending on the shape of moldedproduct, the stretched part of the sheet is orientated throughpreforming, and thus breaking strength or elongation at break wouldincrease, resulting in difficulty in cutting the sheet during the courseof trimming. From the viewpoint of easier and more reliable trimming,the elongation at break as measured at 25° C. is preferably 3 to 7%.

As used herein, the term “elongation at break” refers to the elongationat break as measured on the surface of the decorative sheet forsimultaneous decoration and injection molding in all directionsincluding MD (a flow direction during formation of the base film) and TD(a direction perpendicular to MD). The same shall apply to the casewhere elongation at break is measured at a temperature other than 25° C.

A characteristic feature of the decorative sheet for simultaneousdecoration and injection molding of the present invention resides inthat the sheet has an elongation at break as measured at 120° C. of 200%or more. The decorative sheet, which satisfies this requirement,exhibits good moldability, and good conformability to the moldingsurface of a mold during the course of preforming. No particularlimitation is imposed on the maximum elongation at break as measured at120° C., but an elongation at break of about 400% is sufficient for theproduction of a typical molded product.

In addition, since breakage or a similar problem of the base film isless likely to occur in, for example, a drying step performed when thedecorative layer is printed on the base film, and the decorative sheetis expected to exhibit a certain flexibility when a resin molded productadhered by a decorative sheet is removed from a mold. Therefore,elongation at break as measured at 40° C. is preferably 10% or more. Incontrast, from the viewpoint of registering for printing, preferably,elongation of the decorative sheet is small in a drying step performedwhen the decorative layer is printed on the base film. Therefore,elongation at break as measured at 40° C. is preferably 20% or less.

Elongation at break at each of the aforementioned temperatures ismeasured according to JIS K 7127. At each of the temperatures,elongation at break is calculated from the length of a non-elongatedsample sheet, and the length of the sheet as measured, by means ofTensilon, at the time when the sheet is broken through elongation. Morespecifically, a test piece (width: 10 mm, total length: 150 mm,thickness: 0.125 mm) is provided, and two parallel gauge lines(interval: 50 mm) are formed on a center portion of the test piece. Theinitial distance between chucks is regulated to 100 mm, and the testspeed is regulated to 100 mm/min.

A variety of resins may be employed as a base of the base filmconstituting the decorative sheet for simultaneous decoration andinjection molding of the present invention. Examples of the resin whichmay employed include acrylic resin; thermoplastic polyester resin;polyolefin resins such as polyethylene, polypropylene, polybutene, andolefinic thermoplastic elastomer; styrenic resin; ABS resin; and vinylchloride resin. Of these, acrylic resin or thermoplastic polyester resinis preferred, from the viewpoint of easy attainment of theaforementioned target elongation at break. Particularly, inconsideration of various properties, including transparency, appearance(e.g., luster), weather resistance, chemical resistance, and the surfacehardness of a resin molded product, acrylic resin is most preferred.

Such a resin to be employed is preferably transparent orsemi-transparent so that the below-described decorative layer can beobserved. Gloss of the resin can be regulated through addition of amatting agent.

Examples of the acrylic resin suitable as a base resin includepoly(meth)acrylate, (meth)acrylic acid resin, polyacrylamide, andpolyacrylonitrile. Of these, poly(meth)acrylate is preferred, from theviewpoints of, for example, transparency, thermal resistance, chemicalresistance, and weather resistance. Specific examples ofpoly(meth)acrylates include polymethyl (meth)acrylate, polyethyl(meth)acrylate, polypropyl (meth)acrylate, polybutyl (meth)acrylate,polyhexyl (meth)acrylate, polyoctyl (meth)acrylate, poly(2-ethylhexyl)(meth)acrylate, methyl (meth)acrylate-butyl (meth)acrylate copolymers,methyl (meth)acrylate-styrene copolymers, and acrylic polyols obtainedthrough copolymerization between a (meth)acrylate (e.g., methyl(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, octyl(meth)acrylate, or cyclohexyl (meth)acrylate) and a (meth)acrylic acidester having a hydroxyl group in the molecule (e.g., 2-hydroxyethyl(meth)acrylate or 2-hydroxy-3-phenoxypropyl (meth)acrylate). Of these, amethyl (meth)acrylate-butyl (meth)acrylate copolymer, which has a glasstransition temperature as high as about 80 to about 105° C., isparticularly preferred. The copolymerization ratio (by mass) of methyl(meth)acrylate to butyl (meth)acrylate is preferably 10/2 to 10/6, morepreferably 10/2 to 10/4. The aforementioned acrylic resins may beemployed singly or in combination of two or more species.

Various methods can be employed for forming, from such a base resin, thebase film having the aforementioned specific elongation at break. Forexample, the elongation at break can be regulated by forming the basefilm from an acrylic resin composition or a thermoplastic resincomposition prepared through addition of a filler (e.g., a rubbermaterial such as acrylic rubber, or the aforementioned matting agent) toa base resin such as acrylic resin or thermoplastic polyester resin. Ofthese fillers, a rubber material is most preferred, from the viewpointof easy control of the elongation at break. Examples of the rubbermaterial include acrylic rubber, butadiene rubber, and silicone rubber.Of these, acrylic rubber is most preferred, in consideration oftransparency of the base film.

Examples of the method for adding rubber to a base resin include amethod in which the base resin is physically mixed with the rubber, anda method in which a monomer for producing the base resin iscopolymerized with a monomer constituting the rubber. The amount of therubber to be added to the base resin is about 3 to about 30 parts bymass, preferably about 10 to about 20 parts by mass, on the basis of 100parts by mass of the base resin.

The amount of a filler (e.g., a matting agent) to be added isappropriately determined in consideration of the type of the filler tobe added or the type of a base resin to be employed. The amount of thefiller is generally 1 to 5 mass %, preferably 1 to 3 mass %, on thebasis of the entirety of the resultant resin composition.

Elongation at break as measured at temperatures can be regulated throughcontrol of orientation of the base film. In general, in an orientationdirection, the film is easily broken, and the elongation at breakthereof decreases. In contrast, in a direction perpendicular to theorientation direction, the film is difficult to be broken, and theelongation at break thereof increases.

The thickness of the base film is about 50 to about 300 μm. A thicknessof 50 μm or more is preferred, from the viewpoints of deep-drawmoldability and surface smoothness, whereas a thickness of 300 μm orless is preferred, from the viewpoints of printability and productioncost. The thickness of the base film is more preferably 50 to 200 μm,from the aforementioned viewpoints.

If necessary, the aforementioned base film may be colored with acoloring agent (e.g., a dye or a pigment). Any known coloring agent maybe employed. Examples of the coloring agent which may be employedinclude inorganic pigments such as titanium white, carbon black, rediron oxide, cobalt blue, and chrome yellow; organic pigments such asPhthalocyanine Blue, isoindolinone, and quinacridone; metallic pigmentssuch as aluminum powder; pearlescent pigments such astitanium-dioxide-coated mica powder; and dyes.

If necessary, the resin composition employed for forming the base filmmay contain a variety of additives. Examples of the additives include anantioxidant, a UV-absorbing agent, a photostabilizer, an antifrictionagent, a lubricant, a plasticizer, an antistatic agent, a flameretardant, a coloring agent, an antifungal agent, and an antibacterialagent. The additive to be incorporated into the resin composition may beappropriately selected from known additives in consideration of theintended use of the decorated resin molded product of the presentinvention.

When, for example, the decorated resin molded product of the presentinvention is employed in an application requiring weather resistance,preferably, weather resistance is imparted to the base film. Therefore,in such a case, the aforementioned resin composition, which is amaterial for forming the base film, preferably contains, for example, anorganic UV-absorbing agent such as a benzotriazole-based,benzophenone-based, or salicylic-ester-based UV-absorbing agent; aninorganic UV-absorbing agent such as zinc oxide, cerium oxide, ortitanium oxide in the form of fine particles having a mean particle sizeof about 0.2 μm or less; or a photostabilizer such as a hindered aminephotostabilizer.

The adhesive layer constituting the decorative sheet for simultaneousdecoration and injection molding of the present invention may be formedof any material, which is selected in consideration of the type of theresin constituting a resin molding. When, for example, the resin moldingis formed of a styrenic resin such as acrylonitrile-styrene-butadienecopolymer (ABS) resin, an acrylic resin, or polyvinyl chloride, theadhesive layer is preferably formed of an acrylic resin, a vinylchloride-vinyl acetate copolymer, or a mixture thereof. When the resinmolding is formed of a polyolefin resin, the adhesive layer ispreferably formed of chlorinate polypropylene or a two-component curableurethane resin. The two-component curable urethane resin contains apolyol serving as a base material, and an isocyanate serving as across-linking agent (curing agent). Examples of the polyol to beemployed, which has two or more hydroxyl groups in the molecule, includepolyethylene glycol, polypropylene glycol, acrylic polyol, polyesterpolyol, polyether polyol, polycarbonate polyol, and polyurethane polyol.The isocyanate to be employed is a multi-valent isocyanate having two ormore isocyanato groups in the molecule. Examples of the multi-valentisocyanate which may be employed include aromatic isocyanates such as2,4-tolylene diisocyanate, xylene diisocyanate, and 4,4′-diphenylmethanediisocyanate; aliphatic (or alicyclic) isocyanates such as1,6-hexamethylene diisocyanate, isophorone diisocyanate, hydrogenatedtolylene diisocyanate, and hydrogenated diphenylmethane diisocyanate;and adducts and oligomers of any of the aforementioned isocyanates(e.g., a tolylene diisocyanate adduct and a tolylene diisocyanatetrimer).

The decorative layer constituting the decorative sheet for simultaneousdecoration and injection molding of the present invention is employedfor providing characters, figures, or symbols on the surface of a resinmolding, or for coloring the surface. The thickness of the decorativelayer is generally 0.1 to 20 μm.

The decorative layer is generally formed by use of an ink. The ink to beemployed contains, like the case of a typical ink, a vehicle formed of abinder resin or a similar material, a coloring agent (e.g., a pigment ora dye), and an additive which is appropriately added. The coloring agentmay be a known coloring agent employed in the aforementioned base film.The decorative layer may be formed by use of such an ink through a knowntechnique such as a printing technique (e.g., gravure printing,silkscreen printing, offset printing, or inkjet printing) or handdrawing. The decorative layer may have an arbitrary pattern; forexample, a woodgrain pattern (e.g., a cross-grain or straight-grainpattern), a stone pattern (e.g., a marble or granite pattern), a tiledpattern, a brick pattern, a texture pattern, a character pattern, ageometric pattern, or a solid color pattern.

The binder resin to be employed in the aforementioned ink may be anyresin, which is selected in consideration of the resin compositionemployed for forming the base film. When, for example, the base film isformed of an acrylic resin composition, the binder resin is preferably amixture of a vinyl chloride-vinyl acetate copolymer and an acrylicresin. When the base film is formed of a thermoplastic resincomposition, the binder resin is preferably a two-component curableurethane resin. The vinyl chloride-vinyl acetate copolymer to beemployed generally has a vinyl acetate. content of about 5 to about 20mass % and an average polymerization degree of about 350 to about 900.If necessary, the vinyl chloride-vinyl acetate copolymer may be furthercopolymerized with a carboxylic acid such as maleic acid or fumaricacid.

Examples of the aforementioned acrylic resin include acrylic resins suchas polymethyl (meth)acrylate, polybutyl (meth)acrylate, methyl(meth)acrylate-butyl (meth)acrylate copolymers, and methyl(meth)acrylate-styrene copolymers; and acrylic polyols obtained throughcopolymerization between a (meth)acrylate (e.g., methyl (meth)acrylate,ethyl (meth)acrylate, butyl (meth)acrylate, octyl (meth)acrylate, orcyclohexyl (meth)acrylate) and a (meth)acrylic acid ester having ahydroxyl group in the molecule (e.g., 2-hydroxyethyl (meth)acrylate or2-hydroxy-3-phenoxypropyl (meth)acrylate). These acrylic resins areemployed singly or in combination of two or more species. As usedherein, the term “(meth)acrylate” refers to acrylate or methacrylate.The mixing ratio (by mass) of the vinyl chloride-vinyl acetate copolymerto the acrylic resin is about 1/9 to about 9/1. The two-componentcurable urethane resin may be, for example, any of the aforementionedones employed as a material for forming the adhesive layer.

The decorative sheet for simultaneous decoration and injection moldingincludes the base film and at least the decorative layer providedthereon, and, if necessary, further includes the adhesive layer. Thedecorative sheet may include an additional layer; for example, aconcealing layer provided on the bottom surface of the decorative layer,or a coating layer provided on the top surface of the decorative layer.

The decorated resin molded product of the present invention will next bedescribed.

In the decorated resin molded product of the present invention, noparticular limitation is imposed on the resin material constituting aresin molding (i.e., the resin material to be employed may be anyresin), as long as the resin material is an injection moldablethermoplastic resin or thermosetting resin (including two-componentcurable resin). Examples of such a thermoplastic resin material includevinyl polymers such as polyvinyl chloride and polyvinylidene chloride;styrenic resins such as polystyrene, acrylonitrile-styrene copolymer,and acrylonitrile-butadiene-styrene copolymer resin (ABS resin); acrylicresins such as polymethyl (meth)acrylate, polyethyl (meth)acrylate, andpolyacrylonitrile; polyolefin resins such as polyethylene andpolyproplylene; polyester resins such as polyethylene terephthalate,ethylene glycol-terephthalic acid-isophthalic acid copolymer, andpolybutylene terephthalate; and polycarbonate resin. Examples of such athermosetting resin include two-component curable urethane resin andepoxy resin. These resins may be employed singly or in combination oftwo or more species. If necessary, such a resin may contain an additive;for example, an antioxidant, a heat stabilizer, a UV-absorbing agent, aphotostabilizer, a flame retardant, a plasticizer, a filler (e.g.,powder of an inorganic substance such as silica, alumina, calciumcarbonate, or aluminum hydroxide, wood powder, or glass fiber), alubricant, a mold release agent, an antistatic agent, or a coloringagent.

No particular limitation is imposed on the thickness of the resinmolding constituting the decorated resin molded product, and thethickness is determined in consideration of the intended use of thedecorated resin molded product. The thickness is generally 1 to 5 mm,preferably 2 to 3 mm.

The resin employed for injection molding may be appropriately coloredwith a coloring agent in consideration of the intended use of thedecorated resin molded product. The coloring agent to be employed may bea known coloring agent similar to that employed in the aforementionedbase film.

Next will be described the method for producing the aforementioneddecorated resin molded product of the present invention.

The decorated resin molded product is produced through simultaneousdecoration and injection molding by use of the aforementioned decorativesheet of the present invention. In this simultaneous decoration andinjection molding, during the course of injection molding, thedecorative sheet which has been placed in a mold in advance is unitedwith a fluidized resin injected into the cavity of the mold, whereby thesurface of a resin molding is decorated.

Simultaneous decoration and injection molding may be performed through aconventionally known process; for example, a process in which thedecorative sheet for simultaneous decoration and injection molding issubjected to preforming, a process in which the decorative sheet is notsubjected to preforming, a process in which the decorative sheet issubjected to preheating, or a process in which the decorative sheet isnot subjected to preheating.

When the decorative sheet for simultaneous decoration and injectionmolding is subjected to deep drawing, preferably, a preforming step iscarried out. In contrast, when the decorative sheet is subjected toshallow drawing, a preforming step may be omitted, and the decorativesheet may be molded by means of the pressure of a fluidized resincharged into a mold simultaneously with injection of the resin. When thedecorative sheet is molded by means of the pressure of the injectedresin, a step of preheating the sheet may be omitted, and the sheet maybe heated by means of heat of the resin. In a step of preforming thedecorative sheet, generally, an injection molding mold also serves as avacuum forming mold. However, in the preforming step, before thedecorative sheet is fed into the injection molding mold, the sheet maybe subjected to vacuum forming by means of a vacuum forming mold otherthan the injection molding mold. In the preforming step, preferably, theinjection molding mold also serves as a vacuum forming mold, from theviewpoint of efficient and precise lamination of the sheet. As usedherein, the term “vacuum forming” encompasses vacuum pressure forming.

In the method for producing the decorated resin molded product of thepresent invention, the following steps are sequentially carried out: (A)a step of preforming the decorative sheet, (B) an injection molding stepin which the decorative sheet is laminated on and united with a resinmolding; and (C) a step of removing the resin molding laminated with theentirety of the decorative sheet.

In the production method, the injection molding mold to be employed maybe of a male-female fitting type; i.e., a combination of a female mold(movable mold) having a molding surface of predetermined shape and amale mold (fixed mold) having a protrusion; or may be a combination of aconcave mold (movable mold) having a molding surface of predeterminedshape and a flat mold (fixed mold).

Next will be described a preferred mode of the method of the presentinvention in detail with reference to FIGS. 2 and 3, which show theaforementioned molding step in which an injection molding mold ofmale-female fitting type is employed.

[Step (A)]

In step (A), which is a step of preforming the decorative sheet,firstly, a decorative sheet 100 is disposed on a female mold (movablemold) 70 having a molding surface of predetermined shape so that thebase film of the decorative sheet 100 faces the molding surface.Subsequently, the decorative sheet 100 is heated and softened by meansof a heating plate 90. In this case, preferably, the heating temperatureis equal to or higher than a temperature in the vicinity of the glasstransition temperature of the sheet, and less than the meltingtemperature (or melting point) of the sheet. In general, heating of thesheet is more preferably performed at a temperature in the vicinity ofthe glass transition temperature of the sheet. The expression “atemperature in the vicinity of the glass transition temperature” refersto a temperature falling within a range of the glass transitiontemperature ± about 5° C. As used herein, “a temperature in the vicinityof the glass transition temperature” is generally about 70° C. to about130° C. The heating plate 90 may be a known heating plate, and may beof, for example, a radiation heating type, a conduction heating type, ora dielectric heating type.

The decorative sheet 100 is sandwiched by the female mold 70 and theheating plate 90, and the opening of a cavity 72 is closed. Thethus-closed cavity is evacuated through suction holes 74 provided in thefemale mold 70, and, if necessary, pressurized air is supplied to thesheet through a vent provided in the heating plate 90. The female mold70 and a male mode are generally heated to about 30 to about 50° C.

Through this procedure, as shown in FIG. 2, the decorative sheet 100 isstretched along the molding surface of the female mold 70 so as to comeinto close contact therewith, whereby the sheet is preformed to have apredetermined shape.

[Step (B)]

In step (B) (i.e., an injection molding step), the female mold 70, inwhich the decorative sheet 100 is in close contact with the moldingsurface as described above, and a male mold (fixed mold) 80 are clampedtogether, and subsequently a fluidized resin molding material isinjected into a cavity formed between these molds, followed bysolidification of the material, whereby the decorative sheet 100 islaminated on and united with the thus-formed resin molding.Specifically, the heating plate 90 is withdrawn, and, as shown in FIG.3, the female mold 70 is moved, by means of a reciprocating apparatus75, toward the male mold 80 so that the molds are united together,followed by mold clamping. Thereafter, a fluidized resin moldingmaterial P is injected, through a gate 84 provided in the male mold 80,into a cavity formed between the female mold 70 and the male mold 80until the cavity is filled with the material, followed by solidificationof the material for injection molding. When the resin molding material Pis formed of a thermoplastic resin, the material is fluidized throughheat-melting, and solidified through cooling. When the resin moldingmaterial P is formed of a thermosetting resin, an uncured liquid resincomposition is cured and solidified through chemical reaction. Throughthis step, the decorative sheet 100 contained in the female mold 80 isattached to and united with the thus-formed resin molding.

[Step (C)]

In step (C), the resin molding laminated and united with the decorativesheet is removed from the injection molding mold.

In step (C), the female mold 70 is separated from the male mold 80; theresin molding laminated with the entirety of the decorative sheet 100 isremoved from the female mold; and an excess portion of the decorativesheet provided along the periphery of the resin molding is trimmed, tothereby yield an intended decorated resin molded product.

In the case where the injection molding mold to be employed is acombination of a concave mold (movable mold) having a molding surface ofpredetermined shape and a flat mold (fixed mold), a decorated resinmolded product is produced through steps similar to those describedabove. The decorative sheet employed in the simultaneous decoration andinjection molding method of the present invention may be in the form ofindividual sheet or continuous sheet.

EXAMPLES

The present invention will next be described in more detail by way ofExamples, which should not be construed as limiting the inventionthereto.

Example 1 (1) Preparation of Decorative Sheet

An acrylic film A having a thickness of 125 μm (primary component:polymethyl methacrylate, acrylic rubber content: 30 mass %, UV-absorbingagent content: 1 mass %) was melt-extruded by means of a T-die, and thefilm was brought into contact with a mirror roller of 100° C. at thetime when the resin temperature was 150 to 200° C. for impartingprintability to the film, to thereby yield a continuous-sheet-likeacrylic film having a smooth printing surface. The elongation at breakof the acrylic film as measured at 25° C. was found to be 5% in both MD(a flow direction during film formation) and TD (a directionperpendicular to MD). The elongation at break of the film as measured at120° C. was found to be 240% in MD and 260% in TD.

Subsequently, a woodgrain pattern was formed on the acrylic film throughrotogravure printing by use of a gravure ink, to thereby yield apatterned ink layer serving as a decorative layer. The employed ink wasprepared by adding, to an acrylic resin binder, a pigment containing rediron oxide, chrome yellow, and carbon black, and a dilution solvent (1:1(by mass) mixture of methyl ethyl ketone and ethyl acetate).Subsequently, a coating liquid containing an acrylic resin and a vinylchloride-vinyl acetate copolymer at a ratio by mass of 1:1, andcontaining a dilution solvent (1:1 (by mass) mixture of methyl ethylketone and ethyl acetate) was applied onto the patterned ink layer,followed by drying, to thereby form an adhesive layer having a thicknessof 4 μm. Thus, a decorative sheet was prepared.

Rotogravure printing was performed by means of a three-color rotogravureprinting machine (including three printing units) under the followingconditions: printing speed: 40 m/minute, acrylic film tension: 20 kg/mwidth. Continuous printing was able to be performed without causingbreakage of the film.

(2) Production of Decorated Resin Molded Product

A laminate-type decorated resin molded product was produced throughsimultaneous decoration and injection molding according to the stepsshown in FIGS. 2 and 3 by use of the decorative sheet prepared in (1)above, and a resin molding material; i.e., ABS resin [“Kralastic MTH-2”(tradename), product of Nippon A & L Inc.]. Preforming and injectionmolding conditions are as follows.

<Preforming Conditions>

Heating plate temperature: 300° C.

Distance between heating plate and film: 15 mm (non-contact radiationheating)

Heating time: 5 seconds

Decorative sheet surface temperature: 120° C.

Forming method: vacuum pressure forming

<Injection Molding Conditions>

Injected resin: ABS resin (described above)

Resin temperature: 230° C.

Mold temperature: 50° C. Injection pressure: 140 MPa

Injection time: 3 seconds

Cooling time: 20 seconds

Number of gates: 6

The state of lamination of the decorative sheet in the thus-produceddecorated resin molded product was visually observed, and moldability ofthe decorative sheet was evaluated on the basis of the below-describedcriteria. Also, trimming performance of the decorative sheet wasevaluated on the basis of the below-described criteria. The results areshown in Table 1.

Evaluation Criteria (Moldability of the Decorative Sheet)

O: No wrinkling, blistering, exfoliation, nor breakage is observed inthe decorative sheet.

Δ: Slight wrinkling or blistering is observed in the decorative sheet.

x: Any of wrinkling, blistering, exfoliation, and breakage is observedin the decorative sheet, causing problems in practical use.

Evaluation Criteria (Trimming Performance)

O: Trimming is easily performed, and no flash nor exfoliation of thedecorative sheet is observed at an end portion of the molded product.

Δ: Flash remains on an edge portion of the molded product, due toincomplete trimming of the decorative sheet.

X: Exfoliation of the decorative sheet is observed at an edge portion ofthe molded product.

Example 2

An acrylic film B, which has the same composition as the acrylic film Aexcept that the primary component is polymethyl acrylate, was employedinstead of the acrylic film A, and a continuous-sheet-like acrylic filmhaving a smooth printing surface was formed in a manner similar to thatof Example 1. The elongation at break of the acrylic film as measured at25° C. was found to be 8% in MD and 7% in TD. The elongation at break ofthe film as measured at 120° C. was found to be 210% in MD and 200% inTD.

Subsequently, in a manner similar to that of Example 1, a patterned inklayer and an adhesive layer were provided on the acrylic film, tothereby prepare a decorative sheet. In a manner similar to that ofExample 1, a laminate-type decorated resin molded product was producedthrough simultaneous decoration and injection molding by use of thedecorative sheet.

Table 1 shows the results of evaluation of moldability, trimmingperformance, and continuous printability of the decorative sheet of thethus-produced decorated resin molded product.

Comparative Example 1

An acrylic film similar to that employed in Example 1 was melt-extrudedby means of a T-die, followed by stretching. The acrylic film wasoriented in MD through regulation of drawing speed or regulation ofcontact pressure against a mirror roller, to thereby yield a base filmhaving an elongation at break as measured at 25° C. of 20% in MD and 7%in TD. The elongation at break of the base film as measured at 120° C.was found to be 120% in MD and 200% in TD.

By use of the base film, a decorative sheet and a decorated resin moldedproduct were produced in a manner similar to that of Example 1, followedby evaluation of the decorative sheet in a manner similar to that ofExample 1. The results are shown in Table 1.

Comparative Example 2

The procedure of Example 1 was repeated, except that the acrylic film Awas replaced by an acrylic film C (thickness: 125 μm) formed solely ofpolymethyl (meth)acrylate resin, and that a base film was preparedthrough casting of an acrylic resin solution onto a metallic mirrorbelt, to thereby yield a decorative sheet and a decorated resin moldedproduct. The decorative sheet was evaluated in a manner similar to thatof Example 1. The results are shown in Table 1.

When the base film was subjected to continuous gravure printing in amanner similar to that of Example 1, the film was broken due to solventattack or tensile force during the course of printing, resulting infailure of printing on the base film. Therefore, the base film wassubjected to sheet-fed screen printing.

The elongation at break of the acrylic film as measured at 25° C. wasfound to be 2% in MD and 2% in TD. The elongation at break of theacrylic film as measured at 120° C. was found to be 320% in MD and 350%in TD.

Comparative Example 3

The procedure of Example 1 was repeated, except that a commerciallyavailable polycarbonate film (“Iupilon” (tradename), product ofMitsubishi Engineering-Plastics Corporation) was employed, to therebyyield a decorative sheet and a decorated resin molded product. Thedecorative sheet was evaluated in a manner similar to that of Example 1.The results are shown in Table 1.

The elongation at break of the polycarbonate film as measured at 25° C.was found to be 120% in MD and 130% in TD. The elongation at break ofthe polycarbonate film as measured at 120° C. was found to be 200% in MDand 240% in TD.

TABLE 1 Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 1 Ex. 2 Ex. 3 Elongation at 25° C. MD  5  8  20  2 120 break (%) TD  5  7  7  2 130 120° C. MD 240210 120 320 200 TD 260 200 200 350 240 Moldability of ◯ ◯ Δ ◯ ◯decorative sheet Trimming performance ◯ ◯ X ◯ X Continuous printability◯^(*1) ◯^(*1) ◯^(*1) X^(*2) ◯^(*1)

O*¹: The film was not broken under the printing conditions described inExample 1, and continuous printing was able to be performed.

X²*: The base film was broken under the printing conditions described inExample 1, and printing failed to be performed.

INDUSTRIAL APPLICABILITY

The decorative sheet of the present invention exhibits good moldability,and thus is suitable for forming a decorated resin molded productthrough simultaneous decoration and injection molding. In addition, thedecorative sheet enables easy trimming. Employment of the decorativesheet of the present invention enables production of a decorated resinmolded product of good quality which is used in a variety ofapplications, including an interior material for vehicles, a surfacemember for home electric appliances, and miscellaneous goods.

1. A decorative sheet for simultaneous decoration and injection molding,which is a laminate and which comprises a base film and at least adecorative layer provided on the base film, the decorative sheet havingan elongation at break as measured at 25° C. of 3 to 10%, and anelongation at break as measured at 120° C. of 200% or more.
 2. Adecorative sheet for simultaneous decoration and injection moldingaccording to claim 1, which has an elongation at break as measured at25° C. of 3 to 7%.
 3. A decorative sheet for simultaneous decoration andinjection molding according to claim 1, which has an elongation at breakas measured at 120° C. of 200 to 400%.
 4. A decorative sheet forsimultaneous decoration and injection molding according to claim 1,wherein the base film is formed of an acrylic resin composition.
 5. Adecorative sheet for simultaneous decoration and injection moldingaccording to claim 4, wherein the acrylic resin composition is a resincomposition containing, as a primary component, a polyacrylate and/or apolymethacrylate.
 6. A decorated resin molded product comprising a resinmolding, and a decorative sheet as recited in claim 1, the sheet beingbonded onto the molding, wherein the decorative layer of the decorativesheet is bonded to the molding.
 7. A decorative sheet for simultaneousdecoration and injection molding according to claim 2, which has anelongation at break as measured at 120° C. of 200 to 400%.
 8. Adecorative sheet for simultaneous decoration and injection moldingaccording to claim 7, wherein the base film is formed of an acrylicresin composition.
 9. A decorative sheet for simultaneous decoration andinjection molding according to claim 8, wherein the acrylic resincomposition is a resin composition containing, as a primary component, apolyacrylate and/or a polymethacrylate.
 10. A decorated resin moldedproduct comprising a resin molding, and a decorative sheet as recited inclaim 9, the sheet being bonded onto the molding, wherein the decorativelayer of the decorative sheet is bonded to the molding.